The present invention relates to ventilation devices and more particularly to hoods having air distribution means.
Filter hood units having a filter disposed therein and a filtered gas outlet are known. In addition, hoods having a gas flow diffuser element over the outlet for distributing the gas as it flows from the hood are also known. However, a drawback of the heretofore known hoods is that the diffuser element must be installed in the hood during the manufacturing operations. This, of course, requires that the parameters of the jobsite be known in advance of the manufacture of the hood or that a hood of approximately the right size and diffuser of approximately the right configuration, size and location in the hood be chosen from an assortment of premanufactured "in stock" hood and diffuser devices.
The first above-mentioned alternative is undesirable for the reason that very seldom is it possible to know all the gas flow parameters of a jobsite even with detailed plans to study. More times than not, on-the-job changes must be made to compensate for factors unknown at the planning stage of the jobsite.
The second above-mentioned alternative is also undesirable for the reasons mentioned in regard to the first alternative, and for the additional reason that an air distribution only approximating the desired distribution may be obtainable from "in stock" hood and diffuser devices.